A new one-step method for physical purification and organic modification of sepiolite

Abstract Organo-sepiolite (OSep) is conventionally prepared by two main steps, including purification of sepiolite (Sep) and organic modification procedure. These two steps were completed independently by two factories or production lines. In order to save more water, energy, cost and decrease polluted water, a one-step method to purify and organically modify Sep was proposed. Orthogonal test was used to optimize the conditions. X-ray diffraction demonstrated three impurities, i.e., quartz, calcite and talc, were include in the raw ore. The mass content of Sep in raw ore was 30%. By this one-step method, the crystalline impurities were completely removed. Organic modification did not influence on the crystal structure and morphology of Sep. The organic surfactant was not only used as organic modifier, but also used as flocculant, making OSep was easier to be separated from the dispersion. Zeta potential results demonstrated that dispersant increased the negative charges of Sep surface, enhancing the repulsive force between Sep. And the surfactant destroyed the electrical double layers and decrease the surface negative charges. Surfactant cations were adsorbed on the surface of Sep, resulting in hydrophobic surface. Contact angles and gel volumes indicated the compatibility between OSep and oil. The one-step method could not only purify Sep, but also efficiently modified the surface properties. This procedure is simple, environmentally friendly and cost saving, with high efficiency.